1. Field of the Invention
The present invention relates to isolated polypeptides having lactonohydrolase activity and isolated nucleic acid sequences encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the nucleic acid sequences as well as methods for producing and using the polypeptides.
2. Description of the Related Art
Lactonohydrolases reversibly catalyze the hydrolysis of lactone compounds to hydroxy acids, i.e., they mediate the interconversion between the lactone and acid forms of hydroxy carboxylic acids.
Shimizu et al. (1992, European Journal of Biochemistry 209: 383-390) have disclosed a lactonohydrolase obtained from Fusarium oxysporum. This enzyme preparation stereospecifically hydrolyzes aldonate lactones such as D-galactono-xcex3-lactone and D-glucono-xcex4-lactone. In addition, the Fusarium oxysporum lactonohydrolase catalyzes the asymmetric hydrolysis of D-pantoyl lactone, which can be used as a chiral building block for the synthesis of D-pantothenate (Shimazu and Kataoka, 1996, Annals of the New York Academy of Sciences 799:650-658; Kataoka et al., 1995, Appl. Microbiol. Biotechnol. 44: 333-338; Kataoka et al., 1996, Enzyme Microb. Technol. 19: 307-310). Furthermore, lactonohydrolase irreversibly hydrolyzes a number of aromatic lactones, such as dihydrocoumarin and homogentisic-acid lactone.
The cloning and expression of a Fusarium oxysporum lactonohydrolase gene has been disclosed (WO 97/10341).
It is an object of the present invention to provide improved polypeptides having lactonohydrolase activity and nucleic acid encoding the polypeptides.
The present invention relates to isolated polypeptides having lactonohydrolase activity selected from the group consisting of:
(a) a polypeptide having an amino acid sequence which has at least 95% identity with amino acids 18 to 400 of SEQ ID NO. 2;
(b) a polypeptide encoded by a nucleic acid sequence having at least 95% homology with nucleotides 90 to 1238 of SEQ ID NO. 1;
(c) a variant of the polypeptide having an amino acid sequence of SEQ ID NO. 2 comprising a substitution, deletion, and/or insertion of one or more amino acids;
(d) an allelic variant of (a) or (b); and
(e) a fragment of (a), (b), or (d) that has lactonohydrolase activity;
The present invention also relates to isolated nucleic acid sequences encoding the polypeptides and to nucleic acid constructs, vectors, and host cells comprising the nucleic acid sequences as well as methods for producing and using the polypeptides.
The present invention further relates to methods for preventing microbial biofilm development.